/*
 * $Id: base64.js,v 2.15 2014/04/05 12:58:57 dankogai Exp dankogai $
 *
 *  Licensed under the MIT license.
 *    http://opensource.org/licenses/mit-license
 *
 *  References:
 *    http://en.wikipedia.org/wiki/Base64
 *
 *      VERSION    : version,
 *      atob       : atob,
 *      btoa       : btoa,
 *      fromBase64 : decode,
 *      d64        : nativeDecode,
 *      toBase64   : encode,
 *      e64        : nativeEncode,
 *      ue64       : nativeEncodeUrl,
 *      pe64       : nativeEncodeUrl,
 *      utob       : utob,
 *      encode     : encode,
 *      encodeURI  : encodeURI,
 *      btou       : btou,
 *      decode     : decode,
 *      noConflict : noConflict
 *
 * 支持直接使用方法：
 *
 *  d64(需要做Base64解码的字符串);
 *  e64(需要做Base64加密的字符串，加密后的字符串中会带+等符号，如果是用在做HTTP提交，请用 ue64() pe64())
 *  ue64(需要做Base64加密的字符串，加密后的字符串中的特殊符号会做URLEncode编码，通常用在提交参数加密)
 *  pe64(同ue64)
 */

(function(global) {
  'use strict';
  // existing version for noConflict()
  var _Base64 = global.Base64;
  var version = "2.1.5";
  // if node.js, we use Buffer
  var buffer;
  if (typeof module !== 'undefined' && module.exports) {
      buffer = require('buffer').Buffer;
  }
  // constants
  var b64chars
      = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
  var b64tab = function(bin) {
      var t = {};
      for (var i = 0, l = bin.length; i < l; i++) t[bin.charAt(i)] = i;
      return t;
  }(b64chars);
  var fromCharCode = String.fromCharCode;
  // encoder stuff
  var cb_utob = function(c) {
      if (c.length < 2) {
          var cc = c.charCodeAt(0);
          return cc < 0x80 ? c
              : cc < 0x800 ? (fromCharCode(0xc0 | (cc >>> 6))
                              + fromCharCode(0x80 | (cc & 0x3f)))
              : (fromCharCode(0xe0 | ((cc >>> 12) & 0x0f))
                 + fromCharCode(0x80 | ((cc >>>  6) & 0x3f))
                 + fromCharCode(0x80 | ( cc         & 0x3f)));
      } else {
          var cc = 0x10000
              + (c.charCodeAt(0) - 0xD800) * 0x400
              + (c.charCodeAt(1) - 0xDC00);
          return (fromCharCode(0xf0 | ((cc >>> 18) & 0x07))
                  + fromCharCode(0x80 | ((cc >>> 12) & 0x3f))
                  + fromCharCode(0x80 | ((cc >>>  6) & 0x3f))
                  + fromCharCode(0x80 | ( cc         & 0x3f)));
      }
  };
  var re_utob = /[\uD800-\uDBFF][\uDC00-\uDFFFF]|[^\x00-\x7F]/g;
  var utob = function(u) {
      return u.replace(re_utob, cb_utob);
  };
  var cb_encode = function(ccc) {
      var padlen = [0, 2, 1][ccc.length % 3],
      ord = ccc.charCodeAt(0) << 16
          | ((ccc.length > 1 ? ccc.charCodeAt(1) : 0) << 8)
          | ((ccc.length > 2 ? ccc.charCodeAt(2) : 0)),
      chars = [
          b64chars.charAt( ord >>> 18),
          b64chars.charAt((ord >>> 12) & 63),
          padlen >= 2 ? '=' : b64chars.charAt((ord >>> 6) & 63),
          padlen >= 1 ? '=' : b64chars.charAt(ord & 63)
      ];
      return chars.join('');
  };
  var btoa = global.btoa ? function(b) {
      return global.btoa(b);
  } : function(b) {
      return b.replace(/[\s\S]{1,3}/g, cb_encode);
  };
  var _encode = buffer
      ? function (u) { return (new buffer(u)).toString('base64') } 
  : function (u) { return btoa(utob(u)) }
  ;
  var encode = function(u, urisafe) {
      return !urisafe 
          ? _encode(u)
          : _encode(u).replace(/[+\/]/g, function(m0) {
              return m0 == '+' ? '-' : '_';
          }).replace(/=/g, '');
  };
  var encodeURI = function(u) { return encode(u, true) };
  // decoder stuff
  var re_btou = new RegExp([
      '[\xC0-\xDF][\x80-\xBF]',
      '[\xE0-\xEF][\x80-\xBF]{2}',
      '[\xF0-\xF7][\x80-\xBF]{3}'
  ].join('|'), 'g');
  var cb_btou = function(cccc) {
      switch(cccc.length) {
      case 4:
          var cp = ((0x07 & cccc.charCodeAt(0)) << 18)
              |    ((0x3f & cccc.charCodeAt(1)) << 12)
              |    ((0x3f & cccc.charCodeAt(2)) <<  6)
              |     (0x3f & cccc.charCodeAt(3)),
          offset = cp - 0x10000;
          return (fromCharCode((offset  >>> 10) + 0xD800)
                  + fromCharCode((offset & 0x3FF) + 0xDC00));
      case 3:
          return fromCharCode(
              ((0x0f & cccc.charCodeAt(0)) << 12)
                  | ((0x3f & cccc.charCodeAt(1)) << 6)
                  |  (0x3f & cccc.charCodeAt(2))
          );
      default:
          return  fromCharCode(
              ((0x1f & cccc.charCodeAt(0)) << 6)
                  |  (0x3f & cccc.charCodeAt(1))
          );
      }
  };
  var btou = function(b) {
      return b.replace(re_btou, cb_btou);
  };
  var cb_decode = function(cccc) {
      var len = cccc.length,
      padlen = len % 4,
      n = (len > 0 ? b64tab[cccc.charAt(0)] << 18 : 0)
          | (len > 1 ? b64tab[cccc.charAt(1)] << 12 : 0)
          | (len > 2 ? b64tab[cccc.charAt(2)] <<  6 : 0)
          | (len > 3 ? b64tab[cccc.charAt(3)]       : 0),
      chars = [
          fromCharCode( n >>> 16),
          fromCharCode((n >>>  8) & 0xff),
          fromCharCode( n         & 0xff)
      ];
      chars.length -= [0, 0, 2, 1][padlen];
      return chars.join('');
  };
  var atob = global.atob ? function(a) {
      return global.atob(a);
  } : function(a){
      return a.replace(/[\s\S]{1,4}/g, cb_decode);
  };
  var _decode = buffer
      ? function(a) { return (new buffer(a, 'base64')).toString() }
  : function(a) { return btou(atob(a)) };
  var decode = function(a){
      return _decode(
          a.replace(/[-_]/g, function(m0) { return m0 == '-' ? '+' : '/' })
              .replace(/[^A-Za-z0-9\+\/]/g, '')
      );
  };
  //框架内部使用的方法
  var nativeDecode = function(a){
    if(!a){
      return "";
    }
    if(a.length>4 && a.substring(0,5)=="@b64@"){
      return decode(a.substring(5,a.length));
    }
    return a;
  };
  
  //框架内部使用的方法
  var nativeEncode = function(a,urisafe){
    return "@b64@"+encode(a, urisafe);
  };
  
  var nativeEncodeUrl = function(a,urisafe){
    return "@b64@"+encodeURIComponent(encode(a, urisafe));
  };
  
  var noConflict = function() {
      var Base64 = global.Base64;
      global.Base64 = _Base64;
      return Base64;
  };
  // export Base64
  global.Base64 = {
      VERSION    : version,
      atob       : atob,
      btoa       : btoa,
      fromBase64 : decode,
      d64        : nativeDecode,
      toBase64   : encode,
      e64        : nativeEncode,
      ue64       : nativeEncodeUrl,
      pe64       : nativeEncodeUrl,
      utob       : utob,
      encode     : encode,
      encodeURI  : encodeURI,
      btou       : btou,
      decode     : decode,
      noConflict : noConflict
  };
  // if ES5 is available, make Base64.extendString() available
  //不支持IE
  if (typeof Object.defineProperty === 'function') {
      var noEnum = function(v){
          return {value:v,enumerable:false,writable:true,configurable:true};
      };
      global.Base64.extendString = function () {
          Object.defineProperty(
              String.prototype, 'fromBase64', noEnum(function () {
                  return decode(this)
              }));
          Object.defineProperty(
              String.prototype, 'd64', noEnum(function () {
                  //注意：该方法仅适用于框架内部
                  return nativeDecode(this);
              }));
          Object.defineProperty(
              String.prototype, 'e64', noEnum(function (urisafe) {
                  //注意：该方法仅适用于框架内部
                  return nativeEncode(this,urisafe);
              }));
          Object.defineProperty(
              String.prototype, 'ue64', noEnum(function (urisafe) {
                  //注意：该方法仅适用于框架内部 由于编码后的值中包含了空格等字符，需要做转码，否则提交后会发生变化
                  return nativeEncodeUrl(this,urisafe);
              }));
          Object.defineProperty(
              String.prototype, 'toBase64', noEnum(function (urisafe) {
                  return encode(this, urisafe)
              }));
          Object.defineProperty(
              String.prototype, 'toBase64URI', noEnum(function () {
                  return encode(this, true)
              }));
      };
      global.Base64.extendString();
  }
  
  
  // that's it!
})(this);

if(this['Meteor']) {
  Base64 = global.Base64; // for normal export in Meteor.js
}

var ue64 = Base64.ue64;
var pe64 = Base64.pe64;
var e64  = Base64.e64;
var d64  = Base64.d64;


